This invention relates to a solid-state electrochromic device using a metal foil terminal as a lead-in terminal for electrodes of the device, and a mirror system and CRT (or Cathode Ray Tube) display using the device.
Reversible transitions between colored and colorless states upon oxidation or reduction caused reversibly by application of voltage are called the phenomenon of electrochromism. Electrochromic (hereinafter referred to as EC) devices that use materials presenting such electrochromic features and are designed to change the color states by manipulating voltages are utilized for display devices, light quantity control devices, and the like across various industrial fields.
An example of conventional solid-state EC devices is illustrated in FIG. 6. In a solid-state EC device 30, a lower transparent conductive coating 32 made of indium tin oxide (ITO) or the like is provided on a glass substrate 31, and a groove 32b is formed to provide an insulated portion 32a in part of the lower transparent conductive coating 32. Subsequently, an EC layer 33 made of WO3 or the like, and an upper transparent conductive coating 34 made of ITO or the like are layered thereon in sequence; these layers are covered with a sealant 35 made of epoxy resin or the like, and an opposed glass plate 36. Moreover, the upper transparent conductive coating 34 is in direct contact with the insulated portion 32a, while the lower transparent conductive coating 32 and the upper transparent conductive coating 34 are formed in such a manner as not to short-circuit, so that a terminal of the upper transparent conductive coating 32 may be derived from the insulated portion 32a. Upon application of a direct-current (DC) voltage across the lower transparent conductive coating 32 and upper transparent conductive coating 34 of the solid-state EC device 30, the EC layer 33 gets colored, and upon application of a reverse voltage, the EC layer 33 gets colorless.
Supplying power from an external source to the lower and upper transparent conductive coatings 32, 34 of the solid-state EC device 30 requires a lead-in terminal to be provided. Conventionally, the glass substrate 31 and the lower transparent conductive coating 32 are held with a metal clip 37, and the glass substrate 31 and the insulated portion 32a are held in like manner; then, each clip 37 is fastened with the sealant 35 and used for a lead-in terminal. The opposed glass plate 36 is bonded in such a manner as to guide a terminal portion of the metal clips 37, 37, and thus the width dimension of the opposed glass plate 36 is shorter than the width dimension of the glass substrate 31.
However, difficulty in working metal materials into the metal clip 37 having several tens of micrometers or so that is as small as the thickness of a resin of the solid-state EC device 30 would disadvantageously impose limitations on the width of the opposed glass plate 36 not wider than the width of the glass substrate 31. In addition, insufficient introduction of stress due to a reduced metal thickness would make it difficult for the metal clip 37 to exert a holding power thereof derived from a stress introduced within a resiliency range, disadvantageously impairing operability upon attachment.
Further, if an end face of the glass substrate 31 is curved, the metal clip 37 is hard to curve along the end face of the substrate 31; thus a contact resistance is increased and/or an outer appearance is impaired. These disadvantages would result from application of the solid-state EC device 30 to a mirror, as well.
On the other hand, as is often the case with a normal CRT display, a VDT (video display terminal) hazard prevention filter is externally attached on a front face of a display panel; however, the filter shields from electromagnetic fields of a wide range of wavelengths, so that a whole screen area disadvantageously becomes too dark to provide a clear image.
As shown in FIG. 7, when a conventional solid-state EC device 30 is used for a CRT display filter, the following two approaches are to be adopted for attaching the solid-state EC device 30. This is because the metal clip 37 for applying a voltage to the solid-state EC device 30 are necessitated by workability constraints to use a metal plate of approximately 100 xcexcm in thickness. Moreover, the metal clip 37 basically realizes a holding power against the glass substrate 31 by spring tension, and thus is shaped like a clip. Accordingly, the thickness and shape of the metal plate result in excessive vertical thickness of the metal clip 37. Therefore, the solid-state EC device 30 should be attached on the CRT display with consideration given to the thickness of the metal clip 37.
The first approach is to provide spacing between a solid-state EC device 30A and a CRT 39, as shown in FIG. 7(a). A description will be given herein of the reason why this approach is applicable. Generally, a front face of the CRT 39 is curved as shown in FIG. 7, while the solid-state EC device 30A with an opposed glass plate 36A is made by adhering the opposed glass plate 36A with an epoxy resin, or the like, and is thus difficult to form so as to follow the curved shape. Accordingly, this approach proposes to space the solid-state EC device 30A and the CRT 39 apart so as not to bring the metal clip 37A into contact with the front face of the CRT 39, to avoid the necessity for forming the opposed glass plate 36A so as to follow the curved shape of the front face of the CRT 39. However, this approach would disadvantageously make the CRT display thick frontward by the filter (solid-state EC device 30A), and need a mounting member. It would also be a conceivable approach to work the glass substrate 31A and/or the opposed glass plate 36A as conforming to the curved shape of the CRT 39 in advance, but that would incur extra costs.
The second approach is to bond a solid-state EC device 30B larger than a CRT 40 to the CRT 40, as shown in FIG. 7(b). A description will be given herein of the reason why this approach is applicable. This approach utilizes a glass panel of the CRT 40 as a substitute for an opposed glass plate, while the glass substrate 31A is worked to assume such a shape as conforming to a curved shape of the CRT 40. Then, the solid-state EC device 30B is bonded onto the glass panel of the CRT 40 through an epoxy resin, or the like as a sealant 35B. In this configuration, the epoxy resin as the sealant 35B is several tens of micrometers or so in thickness, but the metal clip 37B is so large as envisaged from the thickness of a metal plate thereof which alone embraces 100 xcexcm or so. Accordingly, if the width dimension of the glass substrate 31B were made shorter than the width dimension of the glass panel, the metal clip 37B would protrude and become an obstacle upon bonding the solid-state EC device 30B to the CRT 40. In view of these circumstances, this approach uses the glass substrate 31B of which the width dimension is greater than that of the glass panel of the CRT 40, and the solid-state EC device 30B is bonded to the CRT 40. Consequently, the metal clips 37B, 37B jut out to the sides of the CRT 40, and thus never become an obstacle. However, this approach disadvantageously results in increase in size of the solid-state EC device 30B as a filter of a CRT display.
The present invention is herein proposed for the purpose of eliminating the above-described disadvantages in prior arts. It is an object of the present invention to provide a solid-state EC device and mirror system using the device, which solid-state EC device has an electrode structure including a terminal that is easy to work into various shapes, and thus contributing to improved operability upon attachment. Further, it is another object of the present invention to provide a CRT display that employs the above device and is thereby adjustable for transmittance or luminance within a specific range.
In order to achieve the above objects, a solid-state EC device according to the present invention comprises a lower transparent conductive layer formed into filmy shape on a glass substrate, partially provided with a groove, and insulated with the groove, an electrochromic layer layered on the lower transparent conductive layer, an upper transparent conductive layer formed into filmy shape over a portion insulated with the groove of the lower transparent conductive layer, and a top of the electrochromic layer, and a sealant and opposed glass plate laminated on the upper transparent conductive layer. In addition, metal foil terminals made of a metal foil to which an electrically conductive adhesive material is applied are bonded to an end of the lower transparent conductive layer and an end of the insulated portion of the lower transparent conductive layer in order to apply a driving voltage to the electrochromic layer. This construction allows the terminals to be attached with ease, and thus achieves improved operability upon attachment.
There is also provided a solid-state EC device as thus constructed in which the metal foil terminals are made of any one of copper and aluminum foils, and/or in which the metal foil terminals have undergone anti-corrosive treatment. These constructions may provide a more reliable solid-state electrochromic device.
Moreover, in order to achieve the above objects, there is provided a mirror system using a solid-state electrochromic device according to the present invention, which comprises a metal reflective coating formed into filmy shape on a glass substrate, a lower transparent conductive layer formed into filmy shape on the metal reflective coating, partially provided with a groove, and insulated with the groove, an electrochromic layer layered on the lower transparent conductive layer, an upper transparent conductive layer formed into filmy shape over a portion insulated with the groove of the lower transparent conductive layer, and a top of the electrochromic layer, and a sealant and opposed glass plate laminated on the upper transparent conductive layer. In addition, metal foil terminals made of a metal foil to which an electrically conductive adhesive material is applied are bonded to an end of the lower transparent conductive layer and an end of the insulated portion of the lower transparent conductive layer in order to apply a driving voltage to the electrochromic layer. This construction easily makes the inventive solid-state EC device applicable to mirror systems.
Moreover, in order to achieve the above object, a CRT display according to the present invention includes a glass panel, and a filter layer formed on a front face of the glass panel, the filter layer being comprised of a solid-state electrochromic device that uses the glass panel for an opposed glass plate, and includes a lower transparent conductive layer and metal foil terminals to which an electrically conductive adhesive material is applied, and the metal foil terminals are located at an end portion of the lower transparent conductive layer. This construction easily makes the inventive solid-state EC device applicable to CRT displays, and thus provides a CRT display adjustable for transmittance or luminance within a specific range.
Further, there is provided a CRT display as described above in which the filter layer comprised of the electrochromic device includes a lower transparent conductive layer formed into filmy shape on a glass substrate, partially provided with a groove, and insulated with the groove, an electrochromic layer layered on the lower transparent conductive layer, an upper transparent conductive layer formed into filmy shape over a portion insulated with the groove of the lower transparent conductive layer, and a top of the electrochromic layer, and a sealant and opposed glass plate laminated on the upper transparent conductive layer. In addition, metal foil terminals made of a metal foil to which an electrically conductive adhesive material is applied are bonded to an end of the lower transparent conductive layer and an end of the insulated portion of the lower transparent conductive layer in order to apply a driving voltage to the electrochromic layer.
In the present invention, the glass substrate is positioned at a lower side, and the opposed glass plate at an upper side, by way of example. It goes without saying that the construction may be illustrated upside down.